1. Field of the Invention
The present invention relates to radio apparatus on the a roadside (namely, an on-road unit) that is provided in a non-stop automatic toll collection system and that is operative to transmit data, which is necessary for toll collection, to and receive such data from a vehicle-mounted unit provided on a vehicle.
2. Description of the Related Art
Generally, when a vehicle enters an expressway from an ordinary road, and, conversely, when a vehicle leaves an expressway for an ordinary road, the vehicle should temporarily stop at a tollbooth (in case where an expressway is toll road), and a driver should receive a toll ticket and pay a toll. Thus, many vehicles often queue up back from the front of the tollbooth.
To prevent an occurrence of a queue of vehicles (or traffic congestion) back from the front of a tollbooth, hitherto, there has been proposed a non-stop automatic toll collection system that can collect tolls without temporarily stopping vehicles at a tollbooth.
It is necessary for realizing such a system to perform transmission/reception of data, which is required to collect tolls, between an on-road unit, which is provided on a road, and a vehicle-mounted unit mounted on a vehicle. In this case, a transmitting antenna and a receiving antenna are attached to an on-road unit. Transmission of necessary data for toll collection is performed between an on-road unit and a vehicle-mounted unit. Thus, non-stop toll collection is performed without causing a vehicle to temporarily stop at a tollbooth.
The aforementioned on-road unit is, however, installed outdoors. It is, thus, necessary to prevent this on-road unit from being damaged by wind, rain, sunlight, and dust. Consequently, there has been an immediate demand that the system has protection means for protecting this on-road unit from wind, rain, sunbeams, and dust.
The present invention is accomplished in view of the aforementioned demand. Accordingly, an object of the present invention is to provide a roadside radio apparatus that can protect a radio device body and an antenna thereof from being damaged by wind, rain, sunlight, and dust, and that shows long-term durability.
According to an aspect of the present invention, there is provided a first roadside radio apparatus for transmitting data, which is necessary for toll collection, to a vehicle-mounted unit mounted on a vehicle and receiving the data therefrom. This roadside radio apparatus comprises a housing, a radio device body accommodated in this housing, and an antenna accommodated in the housing and connected to the radio device body.
With such a configuration, in which the radio device body and the antenna connected thereto are accommodated in the housing, the radio device body and the antenna can be prevented from being damaged by wind, rain, sunlight, and dust. Moreover, a roadside radio apparatus having long-term durability can be provided.
Further, according to a second roadside radio apparatus, which is a modification of the first roadside radio apparatus of the present invention, the housing comprises a base having a radio device body accommodating recess portion and an antenna accommodating recess portion, which are disposed back to back with each other, and using a surface part of the antenna accommodating recess portion as a radio wave reflecting surface, a base cover that covers the radio device body accommodating recess portion of this base and that constitutes a radio device body accommodating portion, which accommodates a radio device body, together with the base, and an antenna cover that covers the antenna accommodating recess portion of the base and that constitutes an antenna accommodating portion, which accommodates an antenna substrate, together with the base.
With such a configuration, in which the radio device body is accommodated in the radio device body accommodating portion consisting of the radio device body accommodating recess portion of the base and the base cover, and in which the antenna is accommodated in the antenna accommodating portion consisting of the antenna accommodating recess portion of the base and the antenna cover, the radio device body and the antenna can be prevented from being damaged by wind, rain, sunlight, and dust. Moreover, a roadside radio apparatus having long-term durability can be provided.
Additionally, electric circuit components of the radio device body can be repaired only by removing the base cover from the base. This enhances the serviceability and assemblability of the apparatus.
Further, according to a third roadside radio apparatus, which is a modification of the second roadside radio apparatus of the present invention, the housing further comprises a radio wave leakage preventing means for preventing radio waves, which are reflected by the radio wave reflecting surface of the base, among radio waves transmitted from the antenna from leaking toward sides of the housing.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, among radio waves transmitted from the antenna substrate, the radio waves reflected by the radio wave reflecting portion of the base can be prevented by the radio wave leakage preventing means from leaking to the sides of the housing. Consequently, an occurrence of a phenomenon of diffraction of radio waves can be prevented.
Further, according to a fourth roadside radio apparatus, which is a modification of the third roadside radio apparatus of the present invention, the radio wave leakage preventing means is constituted in such a way as to block a space provided between the antenna, which is accommodated in the antenna accommodating portion, and the radio wave reflecting portion with a radio wave cutoff member for shutting off a radio wave reflected by the radio wave reflecting portion.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, radio waves transmitted from the antenna substrate and reflected by the radio wave reflecting portion of the base are shut off by the radio wave cutoff member. Thus, the radio waves can be prevented from leaking to the sides of the housing. Consequently, an occurrence of a phenomenon of diffraction of radio waves can be prevented.
Further, according to a fifth roadside radio apparatus, which is an modification of the fourth roadside radio apparatus of the present invention, the radio wave cutoff member is a radio wave cutoff rib formed in the radio wave reflecting portion of the base.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, radio waves transmitted from the antenna substrate and reflected by the radio wave reflecting portion of the base are shut off by the radio wave cutoff rib. Thus, the radio waves can be prevented from leaking to the sides of the housing. Consequently, an occurrence of a phenomenon of diffraction of radio waves can be prevented.
Further, according to a sixth roadside radio apparatus, which is a modification of the second roadside radio apparatus of the present invention, the antenna cover is made of a radio wave transmissive material having good weather-resistance and permittivity.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, the antenna cover can be made of a radio wave transmissive material, for example, an ASA resin, which has good weather-resistance and permittivity.
Further, according to a seventh roadside radio apparatus, which is an modification of the second roadside radio apparatus of the present invention, the antenna is constituted by an antenna substrate. Moreover, the antenna accommodating portion has a distance maintaining means for maintaining the distance L between the antenna substrate and the antenna cover at a value at which characteristics of the antenna are optimum.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, the distance L between the antenna substrate and the antenna cover can be maintained by the distance maintaining means at a value at which the antenna has optimum characteristics. Thus, variation in the characteristic, that is, axial ratio or bandwidth of this antenna can be reduced.
Further, according to an eighth roadside radio apparatus, which is a modification of the seventh roadside radio apparatus of the present invention, the distance maintaining means is accommodated in the antenna accommodating portion in a state in which the antenna substrate is sandwiched between one of spacers and the other spacer. Moreover, an electrically conductive cushion member is provided in the radio wave cutoff rib. Furthermore, this electrically conductive cushion member is made to abut against the antenna substrate.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, because the distance maintaining means is accommodated in the antenna accommodating portion in a state in which the antenna substrate is sandwiched between one of the spacer and the other spacer, the strength of the antenna cover can be increased. Thus, the warpage and deformation of the antenna can be prevented. Moreover, a certain positional relationship between the antenna and the antenna cover can be maintained.
Furthermore, because the antenna substrate is pressed against the antenna-cover-side through the latter spacer by the radio wave cutoff rib, variation in dimensions thereof can be accommodated. Moreover, the distance L between the antenna substrate and the antenna cover can be maintained by this distance maintaining means at a value at which the antenna has optimum characteristics. Thus, variation in the characteristic, that is, axial ratio or bandwidth of this antenna can be reduced.
Further, according to a ninth roadside radio apparatus, which is a modification of the eighth roadside radio apparatus of the present invention, a surface portion of the antenna cover is formed like a sphere, of which radius is R, while an antenna cover facing surface portion of the other spacer is formed as a spherical portion that abuts against the surface portion of the antenna cover.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, the strength of the antenna cover can be increased still more.
Furthermore, according to a tenth roadside radio apparatus, which is a modification of the ninth roadside radio apparatus of the present invention, many projections are formed on the antenna cover facing surface portion of the other spacer.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, when the antenna cover facing surface portion is brought into contact with and pressed against the antenna cover, many projections are crushed, so that variation in dimensions thereof can be accommodated.
Further, according to an eleventh roadside radio apparatus, which is a modification of the second roadside radio apparatus of the present invention, the base comprises a peripheral wall portion having a base-side mating part, and further comprises a screw hole portion, which is disposed at a place that is more inward than this peripheral wall portion, and a packing receiving portion, which is disposed at a place that is more inward than this screw hole portion. Furthermore, the antenna cover comprises a peripheral wall portion having an antenna-cover-side mating portion, which is aligned with the base-side mating portion when attached to the base, and further comprises a screw seat portion disposed at a place that is more inward than this peripheral wall portion, and a packing holding portion disposed at a place that is more inward than this screw seat portion. Moreover, a waterproof packing is provided in the packing receiving portion. Furthermore, in a state in which the antenna cover is attached to the base by aligning the antenna-cover-side mating portion with the base-side mating portion and by screwing screw members, which are inserted into the screw hole portions, into the screw seat portion, the antenna accommodating portion is shut off from the outside by holding the waterproof packing by means of the packing holding portion.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, when the antenna cover is attached to the base by aligning the antenna-cover-side mating portion with the base-side mating portion and screwing the screw members, which are inserted into the screw hole portions, into the screw seat portion, a waterproofing position, at which the packing holding portion holds the waterproof packing, is set in such a manner as to be more inward than a fixing position at which the antenna cover is fixed by the screw members. Thus, the waterproof packing performs the function of preventing water from entering the antenna accommodating portion from the screw hole portions.
Further, according to a twelfth roadside radio apparatus, which is a modification of the second roadside radio apparatus of the present invention, an air escape hole is provided in a surface portion of the base cover, wherein a porous waterproof sheet is provided by being stretched in this air escape hole. Moreover, a mounting seat element is fixed to a front side of the surface portion of the base cover, wherein a notch portion is provided in the mounting seat element. Furthermore, the air escape hole is placed in the notch portion. Further, amounting plate is fixed to the mounting seat element. Moreover, a space provided just above the air escape hole is closed by the mounting plate.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, the porous waterproof sheet is provided by being stretched in the air escape hole. Furthermore, the mounting plate is placed just above the air escape hole. Thus, rainwater can be prevented from entering this air escape hole.
Further, according to a thirteenth roadside radio apparatus, which is a modification of the second roadside radio apparatus of the present invention, a recess portion is provided in a surface portion of the base cover. Moreover, a bottom part of the recess portion has an LED display window portion for checking whether or not an LED of the radio device body, which is accommodated in the radio device body accommodating portion. Furthermore, the LED display window is covered with a transparent panel.
With such a configuration, effects similar to those of the first roadside radio apparatus can be obtained. Moreover, it can be checked from this LED display window portion whether or not the LED of the radio device body is turned on. Thus, a user can judge from the outside whether or not a power supply for the radio device body is out of order.